My favourite answer has been the one by David M. Eagleman, neuroscientist at the Baylor College of Medicine (Texas). According to him, a powerful (and underused) concept is the Umwelt:

...a word to express a simple (but often overlooked) observation: different animals in the same ecosystem pick up on different environmental signals. In the blind and deaf world of the tick, the important signals are temperature and the odor of butyric acid. For the black ghost knifefish, it’s electrical fields. For the echolocating bat, it’s air-compression waves. The small subset of the world that an animal is able to detect is its Umwelt. The bigger reality, whatever that might mean, is called the Umgebung.

It is a powerful idea when applied to ourself; in fact, each organism assumes its Umwelt to be the entire objective reality “out there.” To enliven in the back of our mind the (mysterious) “amount that goes undetected in our lives” can be an ispiring experience. Because, in the words of Eagleman,

It neatly captures the idea of limited knowledge, of unobtainable information, and of unimagined possibilities. Consider the criticisms of policy, the assertions of dogma, the declarations of fact that you hear every day — and just imagine if all of these could be infused with the proper intellectual humility that comes from appreciating the amount unseen.